The Wiki entry on the event.

Even if everything that Zimmerman said is true. And it seems Chris Serino is a Sanford Police homicide detective and was the lead investigator for the police on the night of the shooting, when he stated in an affidavit that he was unconvinced by Zimmerman's version of events.

Zimmerman had no business following the kid. He should have obeyed the instruction of the dispatcher and of the Sanford Police volunteer program coordinator Wendy Dorival.